Layer systems are used in particular for components operated at high temperatures. These are in particular turbine blades or vanes with a metallic substrate, metallic bonding layer and ceramic thermal barrier layer.
In addition, gas turbine components in particular are cooled by a cooling medium flowing out of a cooling hole in order to cool the component on the inside or else in order to protect the component on the outside against excessively hot gases.
Holes of this type are often made after complete coating of the substrate, in which case the opening can then be a flaw or starting point for crack growth on its inner face.